1. Field of the Invention
The present invention relates to a substrate processing apparatus for forming a thin film on a substrate and a method of manufacturing a semiconductor device.
2. Description of the Prior Art
In the related art, a substrate processing apparatus such as a vertical chemical vapor deposition (CVD) apparatus is used to form a thin film on a substrate such as a silicon wafer. The vertical CVD apparatus includes a reaction vessel for processing a substrate, a gas supply line for supplying process gas to the inside of the reaction vessel, and a main exhaust line for exhausting the inside of the reaction vessel.
In a substrate processing method using the vertical CVD apparatus, after carrying a substrate into the reaction vessel, the substrate is processed by supplying process gas to the inside of the reaction vessel while exhausting the inside of the reaction vessel through the main exhaust line, and then the processed substrate is carried out of the reaction vessel.
In the substrate processing method, if the process gas includes vaporized BTBAS (bis(tertiary-butylamino)silane, SiH2[NH(C4H9)]2) and ammonia gas (NH3), a silicon nitride (Si3N4) film may be formed on the substrate (for example, refer to Patent document 1 below).
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2001-230248.
When a substrate is processed according to the above-described substrate processing method, byproducts may be deposited inside the main exhaust line, and the deposited byproducts and their components may flow back into the reaction vessel and adsorb on the substrate accommodated in the reaction vessel to cause problems such as generation of particles (contaminants). If semiconductor devices are fabricated using a substrate on which contaminants are adsorbed, the performance, lifespan, or manufacturing yield of the semiconductor devices is decreased. Generation of contaminants is not limited to the above-described case, for example, contaminants can be generated due to gas phase reaction of process gas in the main exhaust line.
In a method proposed to remove such problems, when carrying a substrate into or out of the reaction vessel or changing the inside of the reaction vessel from vacuum state into atmospheric pressure state, a small amount of gas is exhausted (slow pumping is executed) through the main exhaust line and a slow exhaust line installed in parallel with the main exhaust line so as to prevent backflow of byproducts and their components.
However, although such a method is used, fine contaminants having a particle diameter of 0.1 μm or less are generated to a several hundred level. Therefore, improved contamination preventing technology is necessary to cope with such situations and future miniaturization of semiconductor devices.